NOVEL PROCESS FOR PRODUCING BENZOIC ACID DERIVATIVE

Description

[0001] This invention relates to a method for preparing a compound having a retinoid activity, which is favorable for the production of such a compound on an industrial scale. It also relates to a novel crystal form of 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl] benzoic acid which is useful as a medicament, and a method for preparing thereof.

BACKGROUND OF THE INVENTION

[0002] The compound obtained by this invention has been prepared by allowing tetrahydronaphthylamine derivative to react with monoester terephthalic halide and then subjecting to de-esterification (JP. Unexamd Pat. Publn. No. 61-76440). This method is, however, unfavorable for the production of the objective compound on an industrial scale, because starting amine derivative is not readily available, this amine derivative is toxic to the human body and more complicated steps are required. Moreover, it may be difficult in some cases to say that the obtained compound by this method is suitable for formulation.

Disclosure of the Invention

[0003] This invention provides a method for preparing the objective compound advantageously in the simple procedure, with high purity and yield from the starting material which is readily available on an industrial scale, inexpensive, and not harmful to the human body.

[0004] The present invention provides a process for the preparation of the objective compound (V):


wherein R², R⁷ and R⁹ are independently hydrogen or lower alkyl, and R³, R⁴, R⁵ and R⁶ are independently lower alkyl, which comprises:

(a) subjecting acyl aniline derivative (I):

wherein R¹ is lower alkyl or aryl and R² is the same as above, and 1,4-butyl dihalide derivative (II):

wherein R³, R⁴, R⁵, R⁶ and R⁷ are respectively the same as above, and X is halogen, to Friedel-Crafts reaction in an inert solvent in the presence of a Friedel-Crafts catalyst, thereby obtaining a novel bicyclic amide compound of the general formula (III):

wherein R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are respectively the same as above;

(b) reacting the thus obtained bicyclic amide compound with a halogenating agent and an alcohol in sequence, and the subjecting to acyl exchange reaction with monoester terephthalic halide, thereby obtaining a amide compound of the general formula (IV):

wherein R², R³, R⁴, R⁵, R⁶, R⁷ and R⁹ are respectively the same as above, and R⁸ is lower alkyl; and

(c) hydrolizing this compound.

[0005] In this invention, the term "lower alkyl" refers to an alkyl group of 1 to 4 carbon atoms, examples of which are methyl, ethyl, i-propyl, butyl, i-butyl, t-butyl and the like.

[0006] The term "aryl" refers to a phenyl group, a substituted phenyl group or the like. The substituent replacing the hydrogen of a phenyl ring can be any one of those which are inactive to the reaction, examples of which are lower alkyl, lower alkoxy carbonyl, nitro, halogen and the like.

[0007] As the Friedel-Crafts catalyst used in the step (a), conventional catalysts for Friedel-Crafts reaction can be used, such as Lewis acids (e.g., AlCl₃, AlBr₃, ZnCl₂, ZnCl₄, ZnBr₂, ZnBr₄, BF₃ and a solvation thereof with an ether, SnCl₄, SnBr₄, TiCl₄ and TiBr₄), protoic acids (e.g., sulfuric acid, anhydrous hydrofluoric acid, phosphoric acid, polyphosphoric acid, perchloric acid, chlorosulfonic acid, fluorosulfonic acid, organic sulfonic acids, trifluoroacetic acid, chloroacetic acid, and the like), and cation-exchange resins, metal-cation forming agent (e.g., AgClO₄, AgBF₄, AgPO₄, AgSbF₆, AgPF₆, and AgAsF₆). Particularly preferred are Lewis acids. The molar amount of catalysts to be used is 0.5- to 5-times, preferably 1- to 3-times, and more preferably 1.5- to 2-times the molar amount of acylated aniline to be used as a starting material.

[0008] Although acylated aniline may be used in a molar amount equivalent to that of butyl dihalide, preferable results can be obtained when one of two compounds is used in an excess amount to the other. For example, butyl dihalide is preferably used in amount of 0.5 to 3 moles and more preferably 1.5 to 2 moles per 1 mole of acylated aniline.

[0009] As the solvent, carbon disulfide, ethers, halogenated hydrocarbons, nitro alkanes or the like can be used with halogenated hydrocarbons being particularly desirable.

[0010] The reaction can be conducted at room temperature, or under heating or cooling condition at a temperature from -70°C to 50 °C. Preferred is the reaction at room temperature or under cooling conditions.

[0011] The time enough for the reaction, although it depends upon the reaction temperature, is in the range of 0.5 to 20 hours.

[0012] Examples of the halogenating agent used in the step (b) include phosphorus trihalides, phosphorus oxyhalides, phosphorus pentahalides, thionyl halides and like. Particularly preferred is phosphorus pentachloride. As the alcohol, lower alkanols are preferred and methanol is favorable for use in the production on an industrial scale.

[0013] As the reaction temperature, room temperature is employed or the reaction is conducted under cooling condition. Preferred is the reaction under cooling condition.

[0014] The hydrolysis in the step (c) can be conducted under basic condition at room temperature, or heating conditions. When heating, the reaction can rapidly proceed.

[0015] In other words, 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl]benzoic acid which is one embodiment of this invention can be obtained by the steps of:

(a) subjecting the acylated aniline derivative (I):

and the 1,4-butyl dihalide derivative (II):

to Friedel-Crafts reaction, to give the bicyclic amide compound of the formula (III):

(b) reacting the compound obtained in the step (a) with monoester terephthalic halide to form the compound of the formula (IV):

(c) subjecting the compound (IV) obtained in the step (b) to deesterification.

[0016] According to the method described in the aforementioned prior art reference, JP. Unexamd. Pat. Publn. No. 61-76440, 5,6,7,8-tetrahydro-5, 5,8,8-tetramethyl-2-naphthylamine as a starting material is reacted with monomethyl terephthalic chloride to form the methyl ester of the objective compound, which is then dissolved in a mixture of methanol and water, and the resultant solution is subjected to hydrolysis by the addition of an aqueous solution of sodium hydroxide. Thereafter, crystals obtained by extraction are recrystallized from a mixture of ethyl acetate and hexane to give the objective compound.

[0017] On the other hand, according to the synthesis method of this invention, hydrochloric acid is added just after the hydrolysis, and precipitated crystals are recrystallized from a methanol type solvent to yield the objective compound. For this reason, complicated procedure such as extraction and removal by evaporation required in the prior art method can be omitted and it is therefore possible to successively perform several different steps in the same reaction vessel. Moreover, procedure is simple because the solvent for recrystallization is of the same solvent type as that used in the reaction.

[0018] In this invention, the term "methanol type solvent" refers to methanol or a mixed solvent of methanol and water, which is preferably used. The amount of water to be used is preferably 0.5- to 2-times the amount of methanol, and it is the most preferable that water is used in the same amount as that of methanol.

[0019] The compound of this invention has an extremely high physiological activity, and handling in a closed system is particularly required therefor. From this point of view, the method of this invention can be said to be advantageous in that its procedure is simple in the same vessel.

[0020] It is difficult to obtain 5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthylamine in great quantities at a low price, which amine has been used as a starting material in the prior art method, and generally many amines are hemotoxic.

[0021] In contrast to this, acetanilide used as a starting material in the method of this invention is available in great quantities and is safe to handle.

[0022] The data of the X-ray diffraction patterns (Figures 5 and 6) of 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl]benzoic acid crystals obtained in Example 3 described below as an embodiment of the method of this invention and obtained by the prior art method are shown in Tables 1 and 2, respectively.

Table 1

Peak No.	2ϑ	Intensity ratio	Peak No.	2ϑ	Intensity ratio
1	6.58	2685	18	23.94	677
2	7.84	455	19	26.14	335
3	9.80	177	20	26.84	248
4	11.90	664	21	26.96	310
5	13.24	10000	22	27.16	469
6	15.74	1558	23	27.8	448
7	16.02	1671	24	28.34	332
8	16.80	871	25	28.76	1552
9	17.52	213	26	29.18	202
10	17.76	1069	27	30.2	192
11	18.1	4112	28	31.66	429
12	19.5	2685	29	31.82	213
13	19.86	924	30	33.96	166
14	20.56	256	31	35.56	227
15	21.54	1385	32	35.78	158
16	22.08	1326	33	38.04	237
17	22.48	987	34	38.28	771

Table 2

Peak No.	2ϑ	Intensity ratio	Peak No.	2ϑ	Intensity ratio
1	11.16	10000	19	23.2	599
2	12.56	3560	20	23.62	1187
3	12.98	2908	21	26.32	216
4	13.34	254	22	28.08	489
5	14.3	577	23	28.74	289
6	14.84	901	24	28.94	515
7	16.92	325	25	29.12	392
8	17.12	476	26	29.30	252
9	17.46	212	27	30.78	158
10	18.62	886	28	30.98	424
11	19.02	754	29	31.48	230
12	19.52	348	30	31.60	175
13	19.72	1440	31	31.66	152
14	20.08	4151	32	32.5	189
15	20.94	1632	33	36.04	240
16	21.42	1067	34	37.82	301
17	22.56	432
18	22.86	381

[0023] From the results described above, it is found that the crystals synthesized by the respective methods have different crystal forms. When the properties of these crystals are compared with each other, it is found that the amount of methanol remaining in the crystals of the objective compound according to this invention, which has been used as a solvent for recrystallization, is 50 ppm or less, whereas the amounts of ethyl acetate and hexane remaining in the crystals of the objective compound according to the prior art, which have been used as solvents for recrystallization, are 1200 ppm and 190 ppm, respectively. The latter two values are far beyond the provision established by the Welfare Ministry in Japan that the amount of solvents remaining in end products should not be more than the standard value of 50 ppm. From the viewpoint that the aforementioned compound is also used as a medicament, it is difficult to say that this situation is favorable.

[0024] Moreover, when the grain sizes of the respective crystals are compared with each other, it is found that the crystals according to the method of this invention have uniform grain size of 0.2 mm or less, whereas the crystals according to the prior art have an ununiform grain size of 1 mm of more. For this reason, according to the method of this invention, there is no need to employ any pulverization step in the formulation, which is extremely advantageous.

[0025] As described above, the method of this invention is an excellent one for industrial use, by which the objective compound can be advantageously synthesized by simple procedure in safety with high yield.

Brief Description of the Drawings

[0026] Figure 1 is a diagram showing the IR spectrum of 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl]benzoic acid which is the objective compound synthesized according to the preparing method of this invention. This IR spectrum was obtained by use of Nujol.

[0027] Figure 2 is a diagram showing the IR spectrum of 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl]benzoic acid which was synthesized according to the prior art method. This IR spectrum was obtained by use of Nujol.

[0028] Figure 3 is a diagram showing the thermal decomposition of the objective compound synthesized according to the production method of this invention. This compound melts at 193°C.

[0029] Figure 4 is a diagram showing the thermal decomposition of the objective compound synthesized according to the prior art method. This compound melts at 233°C.

[0030] As can be seen from Figures 3 and 4, the objective compound synthesized by the synthesis method of this invention has the different properties from those of the compound synthesized by the synthesis method of the prior art.

[0031] Figure 5 is a diagram showing the powdery X-ray diffraction of the objective compound synthesized according to the production method of this invention (CuKα, 40kV, and 40mA).

[0032] Figure 6 is a diagram showing the powdery X-ray diffraction of the target compound synthesized by the production method of the prior art (CuKα , 40kV, and 40 mA).

[0033] From Figures 5 and 6, it is found that the target compounds obtained by the different synthesis methods have the respective distinct crystal forms.

[0034] This invention will be further illustrated by the following examples, which are not to be considered as limiting the scope.

Examples

Example 1.1

2,5-dichloro-2,5-dimethylhexane

[0035] First, 48 g (0.328 mole) of 2,5-dimethyl-2,5-hexanediol was suspended in 480 ml of concentrated hydrochloric acid, and the suspension was vigorously stirred at room temperature for 1 hour. After removal of the precipitated crystals by filtration, these crystals were dissolved in 120 ml of CH₂Cl₂. This solution was washed with water, dried over MgSO₄, and then evaporated to dryness, resulting in 49.3 g (82%) of the aforementioned compound. m.p. 65 - 66 °C.
NMRδ (CDCl₃): 1.63 (12H, s, CH₃ x 4), and 1.97 (4H, s, CH₂ x 2).

1,2,3,4-tetrahydro-1,1,4,4-tetramethyl-6-acetaminonaphthalene

[0036] First, 20.28 g (0.15 mole) of acetanilide was suspended in 170 ml of CH₂Cl₂. To this suspension, 42 g (0.15 x 2.0 mole) of AlCl₃ and 48.07 g (0.15 x 1.75 mole) of 2,5-dichloro-2,5-dimethylhexane were added in this order at -15°C, and the mixture was stirred at the same temperature for 2 hours. The reaction mixture was then poured into 700 ml of ice water. After removal of CH₂Cl₂ layer, the aqueous layer was extracted with 100 ml of CH₂Cl₂, then the resulting CH₂Cl₂ layer was mixed with the aforementioned CH₂Cl₂ layer. The combined solution was washed with water, dried over MgSO₄, and then evaporated to dryness, resulting in 61.4 g of the residue. To this residue, 110 ml of n-hexane was added, and the solution was allowed to stand overnight in a refrigerator. Then, 29 g (78%) of the precipitated crystals were recrystallized from a mixture of ethanol and water, resulting in 25 g (67%) of the aforementioned compound having a melting point of 116° to 118°C.
NMRδ (CDCl₃): 1.27 (12H, s, CH₃ x 4), 1.68 (4H, s, CH₂ x 2), 2.13 (3H, s, COCH₃), 7.15 - 7.45 (3H, m, aromatic H); and 7.69 (1H, broad-s, NH).

Examples 1.2 to 1.14

[0037] The same reactions as described in Example 1.1 were conducted under the different reaction conditions, and the results shown in Table 3 were obtained as Examples 1.2 to 1.14.

Example 2

Methyl 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl) carbamoyl]benzoate

[0038] First, 125 g (0.51 mole) of 1,2,3,4-tetrahydro-1,1,4,4-tetramethyl-6-acetaminonaphthalene was dissolved in 625 ml of CH₂Cl₂. To this solution, 206 ml of dimethylaniline and 116.6 g (0.51 x 1.1 mole) of phosphorus pentachloride were added in this order at -25°C under the nitrogen atmosphere, and the mixture was stirred at the same temperature for 1.5 hours. To this reaction mixture was added dropwise 2.06 ℓ of methanol, after which the cooling bath was removed and the stirring of the mixture was continued for 2 hours (at -25°C to room temperature). Furthermore, this reaction mixture was cooled to -25°C, and 306 ml of dimethylaniline and 101.1 g (1.01 x 0.51 mole) of terephthalic chloride were added thereto in this order. The mixture was stirred at -20°C to -30°C for 1 hour. After the reaction was completed, the reaction mixture was poured into 2.6 ℓ of chilled 1N hydrochloric acid, and the mixture was extracted with 1.3 ℓ of CH₂Cl₂. The CH₂Cl₂ layer was washed with 2.6 ℓ of 1N hydrochloric acid, 4 ℓ of water, 5% aqueous solution of sodium bicarbonate and 4 ℓ of water in this order. After drying over MgSO₄, the solution was evaporated to dryness. To this residue was added 740 ml methanol, and the mixture was allowed to stand overnight, resulting in 151 g (81%) of the above-described compound.
NMR (CDCl₃)δ:
1.29 (6H, s, CH₃ × 2); 1.31 (6H, s, CH₃ × 2); 1.72 (4H, s, CH₂ × 2); 3.95 (3H, s, COCH₃); 7.29 (1H, d, J=8Hz, aromatic H); 7.46 (1H, d-d, J=2 and 8Hz, aromatic H); 7.64 (1H, d, J=2Hz, aromatic H); 8.00 (2H, d, J=8Hz, aromatic H); and 8.13 (2H, d, J=8Hz, aromatic H)

Example 3

4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl] benzoic acid

[0039] First, 40 g (0.1094 mole) of methyl 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl)benzoate was suspended in 400 ml of methanol. To this suspension was added a solution of 13.1 g (0.1094 x 3 mole) of sodium hydroxide in 200 ml of water, and the mixture was stirred for 1 hour under reflux by boiling. The reaction mixture was cooled with water, and the pH was adjusted by addition of 2 N hydrochloric acid, whereby the crystals of the objective compound were precipitated. These crystals were recrystallized from a 1:1 mixture of methanol and water to yield 35.4 g (92%) of the objective compound in pure form.
IR (Nujol) cm⁻¹: 3300, 1700, 1645, 1610, 1270, 535
NMR(d₆DMSO)δ:
1.24 (12H, s, CH₃ x 4); 1.67 (4H, s, Ch₂ x 2); 7.30 (1H, d, J=Hz, aromatic H); 8.08 (4H, s, aromatic H); and 10.27 (1H, s)

Claims

1. A method for preparing a benzoic acid derivative of the general formula (V):

wherein R², R⁷ and R⁹ are independently hydrogen or lower alkyl, and R³, R⁴, R⁵ and R⁶ are independently lower alkyl, which comprises:

(a) subjecting acyl aniline derivative of the general formula (I):

wherein R¹ is lower alkyl or aryl and R² is the same as above, and 1,4-butyl dihalide derivative (II):

wherein R³, R⁴, R⁵, R⁶, and R⁷ are respectively the same as above, and X is halogen, to Friedel-Crafts reaction to give a bicyclic amide compound of the general formula (III):

wherein R¹, R², R³, R⁴, R⁵, R⁶, and R⁷ are respectively the same as above:

(b) reacting the compound (III) obtained in the step (a) with a monoester terephthalic halide to form a compound of the general formula (IV):

wherein R², R³, R⁴, R⁵, R⁶, R⁷, and R⁹ are respectively the same as above, and R⁸ is lower alkyl; and

(c) subjecting the compound (IV) obtained in the step (b) to deesterification reaction to give the compound of the general formula (V).

2. A bicyclic amide compound of the general formula (III):

wherein R¹, R², R³, R⁴, R⁵, R⁶, and R⁷ are respectively the same as above.

3. A crystal form of 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl]benzoic acid which exhibits the angles and strength ratios of X-ray diffraction shown in the table below:

2ϑ	Intensity ratio	2ϑ	Intensity ratio
6.58	2685	23.94	677
7.84	455	26.14	335
9.80	177	26.84	248
11.90	664	26.96	310
13.24	10000	27.16	469
15.74	1558	27.8	448
16.02	1671	28.34	332
16.80	871	28.76	1552
17.52	213	29.18	202
17.76	1069	30.2	192
18.1	4112	31.66	429
19.5	2685	31.82	213
19.86	924	33.96	166
20.56	256	35.56	227
21.54	1385	35.78	158
22.08	1326	38.04	237
22.48	987	38.28	771

4. A method for preparing a crystalline 4-[(5,6,7,8-tetrahydro-5,5, 8,8-tetramethyl-2-naphthyl)carbamoyl]benzoic acid claimed in claim 3 comprising the step of recrystallizing a compound of the formula:

from a methanol type solvent.

5. A method for preparing a bicyclic amide compound of the general formula (III):

wherein R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are the same as in claim 1, which comprises subjecting an acyl aniline derivative of the general formula (I):

wherein R¹ and R² are the same as above,
and a 1,4-butyl dihalide derivative of the general formula (II):

wherein R³, R⁴, R⁵, R⁶ and R⁷ are the same as above, and X is halogen,
to a Friedel-Crafts reaction in an inert solvent in the presence of a Friedel-Crafts catalyst.

Ansprüche

1. Verfahren zur Herstellung eines Benzoesäurederivats der allgemeinen Formel (V):

wobei R², R⁷ und R⁹ unabhängig Wasserstoffatome oder Niederalkylreste sind, und R³, R⁴, R⁵ und R⁶ unabhängig Niederalkylreste sind, umfassend:

(a) eine Friedel-Crafts-Reaktion eines Acylanilinderivats der allgemeinen Formel (I):

wobei R¹ ein Niederalkyl- oder Arylrest ist und R² die vorstehend angegebene Bedeutung hat, und eines 1,4-Butyldihalogenidderivats (II):

wobei R³, R⁴, R⁵, R⁶ und R⁷ die vorstehend angegebene Bedeutung haben, und X ein Halogenatom ist, wobei eine bicyclische Amidverbindung der allgemeinen Formel (III):

erhalten wird, wobei R¹, R², R³, R⁴, R⁵, R⁶ und R⁷ die vorstehend angegebenen Bedeutungen haben;

(b) Umsetzung der in der Stufe (a) erhaltenen Verbindung (III) mit einem Monoesterterephthalsäurehalogenid, wobei eine Verbindung der allgemeinen Formel (IV) gebildet wird:

wobei R², R³, R⁴, R⁵, R⁶, R⁷ und R⁹ die vorstehend angegebenen Bedeutungen haben und R⁸ ein Niederalkylrest ist; und

(c) Esterspaltung der in der Stufe (b) erhaltenen Verbindung (IV), wobei die Verbindung der allgemeinen Formel (V) erhalten wird.

2. Bicyclische Amidverbindung der allgemeinen Formel (III):

wobei R¹, R², R³, R⁴, R⁵, R⁶ und R⁷ die vorstehend angegebenen Bedeutungen haben.

3. Kristallform von 4-[(5,6,7,8-Tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl]benzoesäure, die die Winkel und Intensitätsverhältnisse der in der nachstehenden Tabelle gezeigten Röntgenbeugung zeigt:

2ϑ	Intensitätsverhältnis	2ϑ	Intensitätsverhältnis
6.58	2685	23.94	677
7.84	455	26.14	335
9.80	177	26.84	248
11.90	664	26.96	310
13.24	10000	27.16	469
15.74	1558	27.8	448
16.02	1671	28.34	332
16.80	871	28.76	1552
17.52	213	29.18	202
17.76	1069	30.2	192
18.1	4112	31.66	429
19.5	2685	31.82	213
19.86	924	33.96	166
20.56	256	35.56	227
21.54	1385	35.78	158
22.08	1326	38.04	237
22.48	987	38.28	771

4. Verfahren zur Herstellung von kristalliner 4-[(5,6,7,8-Tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carbamoyl]-benzoesäure nach Anspruch 3, umfassend den Schritt der Umkristallisation einer Verbindung der Formel:

aus einem Lösungsmittel des Methanoltyps.

5. Verfahren zur Herstellung einer bicyclischen Amidverbindung der allgemeinen Formel (III):

wobei R¹, R², R³, R⁴, R⁵, R⁶ und R⁷ die in Anspruch 1 angegebene Bedeutung haben, umfassend eine Friedel-Crafts-Reaktion eines Acylanilinderivats der allgemeinen Formel (I):

wobei R¹ und R² die vorstehend angegebene Bedeutung haben, und eines 1,4-Butyldihalogenidderivats der allgemeinen Formel (II):

wobei R³, R⁴, R⁵, R⁶ und R⁷ die vorstehend angegebenen Bedeutungen haben, und X ein Halogenatom ist, in einem inerten Lösungsmittel in Gegenwart eines Friedel-Crafts-Katalysators.

Revendications

1. Procédé de préparation d'un dérivé d'acide benzoïque de formule générale (V):

dans laquelle R², R⁷ et R⁹ représentent indépendamment l'hydrogène ou un groupe alkyle inférieur, et R³, R⁴, R⁵ et R⁶ représentent indépendamment un groupe alkyle inférieur, qui comprend:

(a) la soumission d'un dérivé d'acylaniline de formule générale (I):

dans laquelle R¹ représente un groupe alkyle inférieur ou aryle et R² est le même que ci-dessus, et d'un dérivé de 1,4-dihalogénobutane (II):

dans laquelle R³, R⁴, R⁵, R⁶ et R⁷ sont respectivement les mêmes que ci-dessus, et X représente un halogène, à une réaction de Friedel et Crafts pour donner un composé amide bicyclique de formule générale (III):

dans laquelle R¹, R², R³, R⁴, R⁵, R⁶ et R⁷ sont respectivement les mêmes que ci-dessus;

(b) la réaction du composé (III) obtenu dans l'étape (a) avec un halogénure de monoester téréphtalique pour former un composé de formule générale (IV):

dans laquelle R², R³, R⁴, R⁵, R⁶, R⁷ et R⁹ sont respectivement les mêmes que ci-dessus, et R⁸ représente un groupe alkyle inférieur, et

(c) la soumission du composé (IV) obtenu dans l'étape (b) à une réaction de désestérification pour donner le composé de formule générale (V).

2. Composé amide bicyclique de formule générale (III):

dans laquelle R¹, R², R³, R⁴, R⁵, R⁶ et R⁷ sont respectivement les mêmes que ci-dessus.

3. Forme cristalline de l'acide 4-[(5,6,7,8-tétrahydro-5,5,8,8-tétraméthyl-2-naphtyl)carbamoyl]benzoïque qui présente les angles et rapports d'intensité de diffraction des rayons X indiqués dans le tableau ci-dessous:

2Θ	rapport d'intensité	2Θ	rapport d'intensité
6,58	2685	23,94	677
7,84	455	26,14	335
9,80	177	26,84	248
11,90	664	26,96	310
13,24	10000	27,16	469
15,74	1558	27,8	448
16,02	1671	28,34	332
16,80	871	28,76	1552
17,52	213	29,18	202
17,76	1069	30,2	192
18,1	4112	31,66	429
19,5	2685	31,82	213
19,86	924	33,96	166
20,56	256	35,56	227
21,54	1385	35,78	158
22,08	1326	38,04	237
22,48	987	38,28	771

4. Procédé de préparation d'un acide 4-[(5,6,7,8-tétrahydro-5,5,8,8-tétraméthyl-2-naphtyl)carbamoyl]benzoïque cristallin selon la revendication 3, comprenant l'étape de recristallisation d'un composé de formule:

dans un solvant de type méthanol.

5. Procédé pour la préparation d'un composé amide bicyclique de la formule générale (III) :

dans laquelle R¹, R², R³, R⁴, R⁵, R⁶ et R⁷ sont les mêmes que dans la revendication 1, procédé qui comprend l'opération consistant à soumettre un dérivé d'acylaniline de la formule générale (I) :

dans laquelle R¹ et R² sont les mêmes que ci-dessus et un dérivé de 1,4-dihalogénobutane (II) :

dans laquelle R³, R⁴, R⁵, R⁶ et R⁷ sont les mêmes que ci-dessus et X est un halogène, à une réaction de Friedel et Crafts dans un solvant inerte en présence d'un catalyseur Friedel et Crafts.

Drawing